A method for the constrained design of natural laminar flow airfoils

Bradford, E Green; John, L Whitesides; Richard, L Campbell; Raymond, E Mineck

doi:10.2514/6.1996-2502

Cited by 9 publications

(7 citation statements)

References 7 publications

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“…(2) may become problematic in the leading-edge region. 5 In the present research a new approach is presented for modeling the variation of the streamline curvature normal to the surface. For an iterative design procedure, it is only necessary to consider the variationof the streamlinecurvaturenear the surface.…”

Section: Sc2d Design Methodsmentioning

confidence: 99%

Efficient Inverse Aerodynamic Design Method for Subsonic Flows

Milholen

2001

Journal of Aircraft

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Computational Fluid Dynamics based design methods are maturing to the point that they are beginning to be used in the aircraft design process. Many design methods however have demonstrated de ciencies in the leading edge region of airfoil sections. The objective of the present research is to develop an e cient inverse design method which i s v alid in the leading edge region. The new design method is a streamline curvature method, and a new technique is presented for modeling the variation of the streamline curvature normal to the surface. The new design method allows the surface coordinates to move normal to the surface, and has been incorporated into the Constrained Direct Iterative Surface Curvature CDISC design method. The accuracy and e ciency of the design method is demonstrated using both two-dimensional and three-dimensional design cases.

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Section: Sc2d Design Methodsmentioning

confidence: 99%

Efficient Inverse Aerodynamic Design Method for Subsonic Flows

Milholen

2001

Journal of Aircraft

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“…The majority of research in this field employs inviscid-viscous coupling strategies, making use of boundary-layer codes for the viscous formulation and either a panel method or the Euler equations for the inviscid formulation. 30,31,32,33,34,35,36,37 Although the inviscid/viscous coupling strategies can be computationally cheaper than the higher-fidelity RANS solvers, the industry's trend toward the use of RANS solvers strongly suggests that NLF design tools should follow suit. Recent research making use of RANS solvers to optimize with transition prediction has shown promising results.…”

Section: Iib Rans-based Aerodynamic Shape Optimization For Nlfmentioning

confidence: 98%

Aerodynamic Shape Optimization for Natural Laminar Flow Using a Discrete-Adjoint Approach

Rashad

Zingg

2015

22nd AIAA Computational Fluid Dynamics Conference

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The design of natural-laminar-flow airfoils is demonstrated by high-fidelity, multipoint, aerodynamic shape optimization capable of efficiently incorporating and exploiting laminarturbulent transition. First, a two-dimensional Reynolds-averaged Navier-Stokes (RANS) flow solver has been extended to incorporate an iterative laminar-turbulent transition prediction methodology. The natural transition locations due to Tollmien-Schlichting instabilities are predicted using the simplified e N envelope method of Drela and Giles or alternatively, the compressible form of the Arnal-Habiballah-Delcourt criterion. The boundarylayer properties are obtained directly from the Navier-Stokes flow solution, and the transition to turbulent flow is modeled using an intermittency function in conjunction with the Spalart-Allmaras turbulence model. The RANS solver is subsequently employed in a gradient-based sequential quadratic programming shape optimization framework. The laminar-turbulent transition criteria are tightly coupled into the objective and gradient evaluations. The gradients are obtained using a new augmented discrete-adjoint formulation for non-local transition criteria. The aerodynamic design requirements are cast into a multipoint design optimization problem. A composite objective is defined using a weighted integral of the operating points. A Pareto front is also formed to study and quantify off-design performance. The proposed framework is applied to the single and multipoint optimization of subsonic and transonic airfoils, leading to robust natural-laminar-flow designs.

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“…Despite these difficulties, there has been some research into the utilisation of physics-based transition solvers in aerodynamic optimisation studies. Green et al (7) used inverse design methodologies to match a user-specified target N-factor distribution by altering aerofoil geometry. Gradient-based optimisation of Natural Laminar Flow (NLF) aerofoils in which the adjoints of the full stability Equations were utilised to enable efficient calculation of objective function gradients has been carried out and found to be effective in improving the performance of a baseline design (8,9) .…”

Section: Introductionmentioning

confidence: 99%

Constrained multi-objective aerofoil design using a multi-level optimisation strategy

et al. 2015

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A novel approach for the multi-objective design optimisation of aerofoil profiles is presented. The proposed method aims to exploit the relative strengths of global and local optimisation algorithms, whilst using surrogate models to limit the number of computationally expensive CFD simulations required. The local search stage utilises a re-parameterisation scheme that increases the flexibility of the geometry description by iteratively increasing the number of design variables, enabling superior designs to be generated with minimal user intervention. Capability of the algorithm is demonstrated via the conceptual design of aerofoil sections for use on a lightweight laminar flow business jet. The design case is formulated to account for take-off performance while reducing sensitivity to leading edge contamination. The algorithm successfully manipulates boundary layer transition location to provide a potential set of aerofoils that represent the trade-offs between drag at cruise and climb conditions in the presence of a challenging constraint set. Variations in the underlying flow physics between Pareto-optimal aerofoils are examined to aid understanding of the mechanisms that drive the trade-offs in objective functions.

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A method for the constrained design of natural laminar flow airfoils

Cited by 9 publications

References 7 publications

Efficient Inverse Aerodynamic Design Method for Subsonic Flows

Efficient Inverse Aerodynamic Design Method for Subsonic Flows

Aerodynamic Shape Optimization for Natural Laminar Flow Using a Discrete-Adjoint Approach

Constrained multi-objective aerofoil design using a multi-level optimisation strategy

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